Scanning-aperture electron microscope for magnetic imaging

Abstract

A scanning-aperture electron microscope system and method in which a radiation source generates a radiation beam that is incident upon a surface of a sample material causing electrons to be ejected from the surface. When magnetic imaging is being performed, a polarization rotator polarization-modulates the radiation beam. A scanning-aperture probe having an aperture is positioned in proxiity to the surface of the sample material so that photoelectrons ejected from the surface of the sample material pass through the aperture. A detector detects the electrons passing through the aperture. The electron detector outputs a signal in response to the detected electrons that is used for imaging magnetic and/or spectroscopic features of the surface of the sample material. The resolution of the imaged features is about equal to a size of the aperture.

What is claimed is:  
     
       1. A scanning-aperture electron microscope, comprising: 
       a radiation source generating a radiation beam;  
       a polarization rotator polarization modulating the radiation beam, the polarization-modulated radiation beam being incident upon a surface of a sample material causing electrons to be ejected from the material, the sample material having at least one magnetic domain, the ejected electrons being ejected from the surface of the sample material in accordance with a polarization of the radiation beam that is incident upon the surface of the sample material and a relative orientation of each magnetic domain;  
       a scanning-aperture probe having an aperture, the aperture being positioned in proximity to the surface of the sample material so that electrons ejected from the surface of the sample material pass through the aperture; and  
       an electron detector detecting the ejected electrons passing through the aperture.  
     
     
       2. The scanning-aperture electron microscope according to claim  1 , wherein the electron detector outputs a signal in response to the detected electrons that is used for imaging magnetic features of the surface of the sample material. 
     
     
       3. The scanning-aperture electron microscope according to claim  2 , wherein a resolution of the imaged magnetic features is about equal to a size of the aperture. 
     
     
       4. The scanning-aperture electron microscope according to claim  1 , wherein the electron detector outputs a signal in response to the detected electrons that is used for imaging spectroscopic features of the surface of the sample material. 
     
     
       5. The scanning-aperture electron microscope according to claim  4 , wherein a resolution of the imaged spectroscopic features is about equal to a size of the aperture. 
     
     
       6. The scanning-aperture electron microscope according to claim  1 , further comprising: 
       an optical element disposed between the aperture of the scanning-aperture probe and the electron detector; and  
       a barrier having a pinhole, the pinhole being disposed between the optical element and the electron detector,  
       the optical element and the pinhole operating together for directing electrons ejected from the surface of the sample material having a predetermined electron energy and having a predetermined emission path to the electron detector.  
     
     
       7. The scanning-aperture electron microscope according to claim  1 , wherein the radiation source is a laser. 
     
     
       8. The scanning-aperture electron microscope according to claim  7 , wherein the radiation source is a synchrotron. 
     
     
       9. The scanning-aperture electron microscope according to claim  1 , wherein the radiation source generates photons. 
     
     
       10. The scanning-aperture electron microscope according to claim  1 , wherein the radiation source generates particles. 
     
     
       11. The scanning-aperture electron microscope according to claim  1 , wherein the radiation source generates ions. 
     
     
       12. The scanning-aperture electron microscope according to claim  1 , wherein the radiation source generates x-rays. 
     
     
       13. The scanning-aperture electron microscope according to claim  1 , wherein the radiation source generates visible light. 
     
     
       14. The scanning-aperture electron microscope according to claim  1 , wherein the radiation source generates ultraviolet light. 
     
     
       15. The scanning-aperture electron microscope according to claim  1 , further comprising a measurement controller generating a trigger signal in response to a magnetic field pulse event applied to the surface of the sample material, and 
       wherein the radiation source is responsive to the trigger signal by generating a pulsed radiation beam.  
     
     
       16. A method for generating an image, the method comprising the steps of: 
       generating a polarization-modulated radiation beam;  
       directing the polarization-modulated radiation beam to a surface of a sample material, the sample material having at least one magnetic domain;  
       positioning an aperture of a scanning-aperture probe in proximity to the surface of the sample material so that electrons ejected from the surface of the sample material pass through the aperture, the ejected electrons being ejected from the surface of the sample material in accordance with a polarization of the radiation beam incident upon the surface of the sample material and a relative orientation of each magnetic domain; and  
       detecting the ejected electrons passing through the aperture.  
     
     
       17. The method according to claim  16 , further comprising the step of outputting a signal in response to the detected electrons that is used for generating an image of magnetic features of the surface of the sample material. 
     
     
       18. The method according to claim  16 , wherein a resolution of the imaged magnetic features is about equal to a size of the aperture. 
     
     
       19. The method according to claim  16 , further comprising the step of outputting a signal in response to the detected electrons that is used for generating an image of spectroscopic features of the surface of the sample material. 
     
     
       20. The method according to claim  19 , wherein a resolution of the imaged spectroscopic features is about equal to a size of the aperture. 
     
     
       21. The method according to claim  16 , wherein the step of detecting the electrons passing through the aperture includes the step of detecting electrons ejected from the surface of the sample material that have a predetermined electron energy and having a predetermined emission path. 
     
     
       22. The method according to claim  16 , wherein the radiation beam is generated by a laser. 
     
     
       23. The method according to claim  16 , wherein the radiation beam is generated by a synchrotron. 
     
     
       24. The method according to claim  16 , wherein the radiation beam is a beam of photons. 
     
     
       25. The method according to claim  16 , wherein the radiation beam is a beam of particles. 
     
     
       26. The method according to claim  16 , wherein the radiation beam is a beam of ions. 
     
     
       27. The method according to claim  16 , wherein the radiation beam is a beam of x-rays. 
     
     
       28. The method according to claim  16 , wherein the radiation beam is a beam of visible light. 
     
     
       29. The method according to claim  16 , wherein the radiation beam is a beam of ultraviolet light. 
     
     
       30. The method according to claim  16 , further comprising the step of generating a trigger signal in response to a magnetic field pulse event applied to the surface of the sample material; and 
       generating a pulsed radiation beam in response to the trigger signal, and  
       wherein the step of directing the radiation beam to the surface of the sample material directs the pulsed radiation beam to the surface of the sample material.